Biological Clocks and Rhythms in Polar Organisms

Abstract

Biological clocks are universal to all living organisms on Earth. Their ubiquity is testament to their importance to life: from cells to organs and from the simplest cyanobacteria to plants and primates, they are central to orchestrating life on this planet. Biological clocks are usually set by the 'beat' of the day-night cycle, so what happens in polar regions during the Polar Night or Polar Day when there are periods of 24 hours of darkness or light? How would a biological clock function without a time-keeper? This chapter details evidence that biological clocks are central to structuring daily and seasonal activities in organisms at high latitudes. Importantly, despite a strongly reduced or absent day night cycles, biological clocks in the Polar Night still appear to be regulated by background illumination. Here we explore evidence for highly cyclic activity, from behaviour patterns to clock gene expression, in copepods, krill and bivalves. The ultimate goal will be to understand the role of endogenous clocks in driving important daily and seasonal life cycle functions and to determine scope for plasticity in a rapidly changing environment.

Fish in Kongsfjorden under the influence of climate warming

“…Given that in 2013 and 2022, data were collected during the "day" (08.45 -17.00 UTC) and "night" (00.10 -04.00 UTC) periods (Table 1), respectively, the second hypothesis proposes an interpretation of the results, taking into account the possible Diel Vertical Migration (DVM) of medium-size fish. Previous studies (Falk-Petersen et al, 2008;Last et al, 2020;Pettitt-Wade et al, 2021) have confirmed that biological clocks of marine organisms are important for shaping their daily activities at high latitudes, and there are some confirmations that organisms could perform DVM in the Arctic during the Polar Night or Polar Day.…”

Reproduction of Marphysa sanguinea Annelida, Polychaeta (Eunicidae), at Mount Edgecombe, Plymouth, near the type locality in Southwest England

“…It is not unreasonable to suppose that in M. sanguinea a similar repertoire of entrained biological rhythms may exist, as has been demonstrated in other large polychaetes with a large supra-oesophageal ganglion and well-developed sensory system, but more amenable to experimental investigation (Watson et al ., 2000a; Last and Olive, 2004; Olive et al ., 2005); notably in Platynereis dumerilli (Audouin and Milne Edwards, 1883), which has become the standard polychaete genomic model (Zantke et al ., 2014). Such biological rhythms are also observed in diverse geographic regions (Last et al ., 2020).…”

The role of continental shelf bathymetry in shaping marine range shifts in the face of climate change

“…The intensity of light decreases exponentially with depth and can restrict the productivity of photosynthetic organisms like seagrasses and coral symbionts (Duarte, 1991; Kahng et al, 2019; Lesser et al, 2021). Light can also constrain latitudinal shifts because highly seasonal diel cycles lead to reduced nutrient availability and limited opportunities for visual foraging in the winter (Chen & Wang, 2016; Last et al, 2020; Ljungström et al, 2021).…”